Polymeric micellar paclitaxel, cisplatin, and tislelizumab as first-line therapy for advanced unresectable esophageal squamous cell carcinoma: A phase II study with resistance profiling in poor responders

Objective

To evaluate the efficacy and safety of polymeric micellar paclitaxel (Pm-Pac), cisplatin, and tislelizumab as first-line therapy for advanced/metastatic esophageal squamous cell carcinoma (ESCC), addressing limitations of conventional paclitaxel regimens related to steroid-induced immunosuppression.

Methods

This phase II clinical trial enrolled 27 treatment-naïve patients with stage IV ESCC. The regimen consisted of Pm-Pac (230 mg/m²), cisplatin (70 mg/m²), and tislelizumab (200 mg) administered on day 1 of 21-day cycles. After two induction cycles, non-progressive patients received two additional cycles, followed by 12-month tislelizumab maintenance. Primary endpoint: objective response rate (ORR); secondary endpoints: progression-free survival (PFS), overall survival (OS), disease control rate (DCR), and safety. Exploratory analyses included blood counts, tumor markers, lymphocyte subsets, survival analysis, Kruskal-Wallis tests, clustering, and LASSO regression.

Results

The regimen achieved an ORR of 62.96 % (95 % CI: 0.45–0.81) with complete response (CR) in 7.4 % and partial response (PR) in 55.6 % of patients. Median PFS was 10.2 months, with 1-year OS probability of 81.48 %. Treatment was well-tolerated without grade ≥ 3 treatment-related adverse events or deaths. Exploratory predictive analyses suggested potential correlations between outcomes and hyperkalemia, CD4 +CD25 + T cells, lung metastases, and distant lymph node metastases.

Conclusions

The Pm-Pac-based chemoimmunotherapy suggests encouraging efficacy and favorable safety in advanced ESCC, supporting its potential as a first-line steroid-free option. These findings highlight the role of nanotechnology in optimizing chemoimmunotherapy.